A picosecond ytterbium-doped fiber laser with average power of 30 W is constructed with a tri-stage master oscillator power amplifier (MOPA) configuration. The laser exhibits a pulse width of 20 ps,repetition rate of 59.8 MHz,and a beam quality M2 of less than 1.5. The diameter of the output fiber core is 30 μm. By using the laser as a pump source,near 3 W supercontinuum is generated from a section of homemade photonic crystal fiber (PCF) with 7 μm core diameter. An extra section of fiber with 15 μm core diameteris arranged between the picosecond laser source and the PCF so as to increase the coupling efficiency and avoid fiber facet damage. The supercontinuum covers the whole spectral range from 600 to 1700 nm of the optical spectrum analyzer. The unflatness of the spectrum is less than 10 dB (except for the residual pump laser peak at 1064 nm). The output beam spot is a white fundamental mode with a chromatic hexagonal surrounding.